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TR4/4A Front lower suspension brackets - TR4A

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fpstude

fpstude

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In a current thread alanjohnturer mentions checking the brackets that hold the front lower suspension pan to the frame. Can this be clarified? I've had our Triumph for 47 years and am not aware of this, and for safety, would like to check it out.
 
I've rebuilt my front end and all I recall is replacing the inner lower bushings, quite a job, and checking the torque on the nut that holds the single stud control arm bracket to the frame. Some folks recommend adding the double stud TR6 setup in place of the 4A one stud setup--if I recall correctly. I'm not convinced that is necessary as British Leyland couldn't be that wrong---I'd hope.
 
We have done a lot with this on the UK TR Register forum. I'll try to find some links.
But you are welcome to search. It searches well without a login, just using Google.

I'll try to make it clear what parts its about. On a 4A the A-shaped lower front spring-pan is connected to the frame by a different method to on a 4.

There are two square box shaped "turrets" welded to the frame tubes. These carry U-shaped brackets that sit around the ends of the cast steel arms that form the A-shaped pan.

There is a cross bolt that goes through the bush in the end of these arms and all this is sound.

The problem is that the U-shaped bracket only fixes to the box-shaped turret with one stud.
There are two failure mechanisms. The brackets develop cracks around the stud and the studs fatigue through.

In the UK we always drill both parts an add another bolt/nut about 1in below the existing one.

The box-shapped turrets are also prone the rust/cracks and this whole area is not as good a design as the original TR4 method.
 
I just did this during an upgrade to my 4A suspension. Buy some used TR 6 brackets (4 are needed) drill an extra hole in the uprights and in my case I added a drilled plate behind the uprights to spread the support. I also used lock washers and a regular washer instead of the nylock nuts. While you are at it this is a good time to inspect and replace any worn rubber bushings in the upper and lower A arms as well as the trunnions and bushings. TRF supplies an entire kit for this job. If you are not comfortable using a spring compressor then take it to a british car specialist and have them do the work.
I last did my front suspension in 1988 and it was shot when I did it again this spring. One of the most concerning things that I found was how loose the single stud nylock nuts had become, just slighly tighter than finger tight.
 
You have see then exact problem. The one stud stretches and allows movement to build up. Then the cracks start.
The rear reinforcement is also a goo idea. I rebuilt mine with 1/8in high-tensile plate.

If you are not doing many miles and don't drive hard then the one-stud is probably OK. But rember all this stuff is getting old.

Also our rooads have many more bends and roundabouts so front suspension parts get a lot of cyclic loading.
Then there is all the hill-climbing and track-racing that goes on.
 
Hi

The book "How to Restore a Triumph TR4" covers this TR4A deficiency on pp.75-76. Parts-wise, TRF has everything. Repairs in order of increasing difficulty involve the following:

  • Square Plate Backing Washer
    • Bolted behind chassis support bracket
    • TR6 retrofit to TR4A
    • TRF #TRFCD137 - 4 required at $3.50 each
    • Nyloc nuts #YN2909 4 (or 8 if you upgrade to the 2nd stud below)
    • Washers #WM59 4 or (or 8 if you upgrade to the 2nd stud below)
  • Fulcrum Bracket Assembly
    • TR6 w/ 2 studs, not 1 – chassis support bracket will need to be drilled for extra hole
      • Use square plate backing washer as template to drill holes
    • TRF#148691
    • 4 required at $24 each
  • Bracket/ Gusset Strengthening Kit
    • 6 gussets to be welded to chassis support bracket
    • TRF #RFK158
    • 1 required at $47 each
  • Chassis Support Bracket (welded to chassis)
    • TR6 type with 2 holes
    • TRF #139580
    • 4 required at $24 each
    • Option is to drill extra hole in each of the four existing brackets

While I have documented how to do this, I've yet to do it myself. It is on "future projects" list.

Bob
 
I just noticed the comment about the spring compressor. I allways use 1/2dia studding right down through the centre of the spring.

At the bottom I have a bracket thing welded from angle. There is no way the spring can jump out at you with this setup. A TR is the only front-spring I will work on because of this.

A friend who was a full-time pro-repairer lost an eye when his "hooked" compressor let go.
 
I did this update on my original TR4A and it's shown in Kastner's Competition Prep manual. Since they made this a standard change on the TR6 it seemed like probably a good thing to do on the TR4A which has the same suspension. At the time that I did the original rebuild (early 1980s), it was very cheap and easy to pick up used TR6 brackets so I just had to drill the extra holes for the second stud and I also added a rear reinforcement plate.

Scott
 
I sure appreciate all of the constructive comments. I don't drive aggressively, but here in California the roads get worse every year as the state is broke. I'll be checking out the front suspension in detail.
 
TRF sells the reinforcement plate for the rear of the upright but it's made for the TR6 upright. Using it on a TR4A one must cut about 3/8 inch off the bottom so that it clears the TR4A frame. The uprights are different on a 4A and a 6. I had a machine shop cut them and then they worked fine. Team Triumph in Warren, OH has the used TR6 brackets for not much money.
 
I had a bracket break on me, so it can happen, back when I had my 4A, as I recall it let go while very gently applying brakes as I was going in reverse with the wheels turned in a parallel parking marking maneuver. Hardly spirited or speedy driving. Heard a small pop and steering went slightly wonky. Glad it didn't let go when I was driving faster.
 
If your existing brackets are sound then you can use them by drilling and using a nut/bolt instead of a stud.

If you do this then use a split lock-washer under the bolt head. Then you will be able to tighten the nut with the suspension arm in place.

Or you can wel the bolt head to the bracket. Personally I dont like welds on parts likely to crack.
 
For all I know, the weak points of these cars are many. I noted these lovely thought-provoking comments by another TR owner from the linked posts: "I have particular reason for seconding your comments re death by fire. If a standard TR 2-6 . . . lands upside down, the likelihood is that it will be flat and it will catch fire . . . . and if the occupants are not already dead on impact, if it does ignite then the likelihood of avoiding cremation whilst still screaming is sod all. The hood/surrey/hardtop/windscreen frame won't help. You really do not want to go there."

I've often thought that a tie rod could break, a ball joint could break, the stub axle could break or even the steering lever arm could break. Then again, the likelihood of an old lady coming through a light in a Buick is out there, too. Not sure where to stop the worrying. Reminds me of when I got hit by a falling tree branch. ____ happens.

I'll take a look at those brackets. I'd want to know that I wasn't weakening anything by drilling holes and welding plates.
 
I know Spits and GT6s aren't TR4 class, but I used to cross a series of RR tracks in St. Louis as I went to work. Got to where it was like jumping in Motocross and when I was in a hurry would clear all tracks at once. One day I decided after about 70k miles to put on new shocks. While undoing the lower shock bolts the lower mount on shock fell off. Looking farther the lower A-arm had oval bolt holes in the bushing ends. Had to get new A-arms. Something to watch for in the older Triumphs.
 
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